The vast majority of nutrients and sediment washed into streams flowing into the Chesapeake Bay are picked up by deluges from severe storms that occur on relatively few days of the year. That is the conclusion of a new study led by Penn State researchers, who say it offers clues for cleaning up the impaired estuary.
“A small percentage of locations and events contribute to the vast majority of total annual pollution loads entering the bay,” said Heather Preisendanz, associate professor of agricultural and biological engineering, College of Agricultural Sciences. “These findings stress the importance of concentrating our efforts on ‘hot moments’ — not just ‘hot spots’ — across impaired watersheds to achieve water-quality-restoration goals.”
Researchers analyzed eight years of data from 108 sites in the Chesapeake Bay Program’s nontidal monitoring network. They looked at daily-scale records of flow and corresponding loads of total nitrogen, total phosphorus and total suspended sediment at each gauging station from 2010 through 2018. Then, in an innovative move, they applied a formula normally used in economics to the data to determine the distribution of pollution loads throughout the years.
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Image: Researchers analyzed eight years of data from 108 sites in the Chesapeake Bay Program's nontidal monitoring network, looking at daily-scale records of flow and corresponding loads of nitrogen, phosphorus and suspended sediment. (Credit: Heather Preisendanz research group/Penn State)